Single-Step Resection of Sphenoorbital Meningiomas and Orbital Reconstruction Using Customized CAD/CAM Implants

摘要

Objective?Computer-aided design and manufacturing (CAD/CAM) implants are fabricated based on volumetric analysis of computed tomography (CT) scans and are routinely used for the reconstruction of orbital fractures. We present three cases of patients with sphenoorbital meningiomas that underwent tumor resection, orbital decompression, and orbital reconstruction with patient specific porous titanium or acrylic implants in a single procedure.Methods?The extent of bone resection of the sphenoorbital meningiomas was planned in a virtual three-dimensional (3D) environment using preoperative thin-layer CT data. The anatomy of the orbital wall in the resection area was reconstructed by superimposing the contralateral unaffected orbit and by using the information of the neighboring bony structures. The customized implants and a corresponding craniotomy template were designed in the desired size and shape by the manufacturer.Results?All patients presented with a sphenoorbital meningioma and exophthalmos. After osteoclastic craniotomy with the drilling template, orbital decompression was performed. Implant fitting was tight in two cases and could be easily fixated with miniplates and screws. In the third patient, a reoperation was necessary for additional bone resection, as well as drilling and repositioning of the implant. The postoperative CT scans showed an accurate reconstruction of the orbital wall. After surgery, exophthalmos was substantially reduced and a satisfying cosmetic result could be finally achieved in all patients.Conclusions?The concept of preoperative 3D virtual treatment planning and single-step orbital reconstruction with CAD/CAM implants after tumor resection involving the orbit is well feasible and can lead to good cosmetic results. Keywords: CAD/CAM implants, single-step, meningioma, orbital decompression, craniotomyIntroductionOrbital lesions, such as sphenoorbital meningiomas exert a mass effect and can cause exophthalmos and visual disturbance by compression of the optic nerve.~(1)Surgical therapy of sphenoorbital tumors consists of tumor resection and/or orbital decompression with subsequent reconstruction of the bony defects.~(1)~(2)~(3)To achieve good functional and aesthetic results, restoration of the orbital walls with perfect symmetry is required. However, due to the complex anatomy of the orbital cavity and its surrounding structures, orbital reconstruction remains a challenge for craniofacial surgeons and neurosurgeons.The conventional approach for reconstructive cranioplasty consists of using bone grafts, biomaterials (e.g., titanium) with a preformed shape, or bone cement.~(4)These are established methods for reconstruction of bony defects and their use is timesaving and inexpensive. However, due to the complex geometry of the orbital cavity with several planes of curvature and different thickness, restoration of the original shape is particularly challenging for orbital lesions and a good functional and aesthetic outcome cannot be guaranteed.~(5)Owing to the advances in computer-aided design (CAD) and computer-aided manufacturing (CAM), custom-made, and individually tailored implants are widely used for cranioplasty of a predefined defect.~(6)~(7)CAD/CAM implants are manufactured based on volumetric analysis of computed tomography (CT) scans and are already routinely used for cranioplasty reconstruction of orbital fractures.~(8)In contrast, single-step orbital decompression and reconstruction with prefabricated customized CAD/CAM implants as surgical strategy for treatment of sphenoorbital lesions represents a new concept and has not been well documented in the literature.In the current article, we present three cases of patients that underwent orbital decompression for sphenoorbital meningiomas and orbital reconstruction with customized porous titanium or acrylic implants during the same operation. These implants were manufactured preoperatively based on a three-dimensional (3D) CT reconstruction and virtual surgical planning of the craniotomy and resection margins in a 3D CAD environment.MethodsWe report surgical details and clinical outcomes of three patients that underwent orbital decompression and cranioplasty with CAD/CAM implants in a single procedure. According to the institutional guidelines, an ethics committee approval was not required for this retrospective studyFabrication of the CAD/CAM ImplantsAfter clinical and radiological diagnosis of a sphenoorbital meningioma and decision toward single-step surgery, the patients received a preoperative thin-layer 64-slice multidetector cranial CT scan with 0.5?mm slice thickness (Philips iCT or Philips Brilliance 64, Philips, Best, The Netherlands) that allows 3D reconstruction of the bony structures. The respective DICOM data (Digital Imaging and Communications in Medicine) were provided to the manufacturing company of the CAD/CAM implants (Anatomics Pty Ltd, St Kilda, Australia). After a digital 3D reconstruction of the sku